The claims of this application benefit of Japanese Application Nos. 2000-000638, 2000-000778, 2000-048750 and 2000-093233 filed in Japan on Jan. 6, 2000, Jan. 6, 2000, Feb. 25, 2000 and Mar. 30, 2000 respectively, the contents of which are incorporated by this reference.
The present invention relates to image display apparatus and, more particularly, to a head- or face-mounted image display apparatus that can be retained on the observer""s head or face.
Image display apparatus designed to observe an image of a single image display device with two eyes have heretofore been known in Japanese Patent Application Unexamined Publication Number [hereinafter referred to as xe2x80x9cJP(A)xe2x80x9d] 5-176260, 9-61748, 9-181998 and 9-181999.
An illuminating method for an image display apparatus designed to observe an image of a single image display device with two eyes has been known, for example, in JP(A) 7-318851.
Among them, the image display apparatus of JP(A) 5-176260 splits and folds light rays by a prism in the shape of an isosceles triangular prism and a mirror. Therefore, various aberrations are corrected by a lens placed in front of the pupil. This makes it difficult to correct aberrations, and at the same time, causes the apparatus to become large in size. In JP(A) 9-61748, display light from an LCD (liquid crystal display device) is split by using a half-mirror so as to be observed with two eyes. Because the display light is distributed to the left and right eyeballs, the image for observation becomes weak and dark. In JP(A) 9-181998 and 9-181999, because prisms are integrated, the prism structure is very large in size and requires a great deal of time and cost when it is produced by injection molding. In addition, correction of decentration aberrations is insufficient.
Regarding an illuminating method for use in a case where a display image from a single display device is observed with two eyes, when an arrangement such as that disclosed in JP(A) 7-318851 is adopted, because images led to the left and right eyes are in reversed relation to each other, the display image needs to be electrically switched for the left and right by the display device or other device.
The present invention was made in view of the above-described problems with the prior art, and an object of the present invention is to provide an image display apparatus, e.g. a head-mounted image display apparatus, in which an image from a single image display device is led to two eyes without using a half-mirror, thereby allowing observation of a bright image, and in which a power is given to an optical path distributing means placed at the middle between the two eyes to facilitate the correction of various aberrations. In addition, an object of the present invention is to provide an illuminating method which is the most suitable for observation of a single panel (single image display device) with two eyes, and which can be used without the need to switch the display image for the left and right.
An image display apparatus according to the present invention provided to attain the above-described object has an image display device for displaying an image to be observed by an observer, an optical path distributing mirror for distributing the image to an optical path for a right eye and an optical path for a left eye, an ocular prism for the right eye that is placed on the right-hand side of the optical path distributing mirror, and an ocular prism for the left eye that is placed on the left-hand side of the optical path distributing mirror.
The optical path distributing mirror has a mirror surface placed to face the image display device to reflect a display light beam emanating from the image display device so as to distribute the display light beam to the ocular prism for the right eye and the prism for the left eye. The mirror surface has a rotationally asymmetric curved surface configuration that corrects decentration aberrations.
The ocular prism for the right eye has a first surface through which the light beam of the optical path for the right eye reflected by the optical path distributing mirror enters the prism, a second surface which reflects the light beam of the optical path for the right eye within the prism, and a third surface through which the light beam of the optical path for the right eye exits from the prism.
The ocular prism for the left eye has a first surface through which the light beam of the optical path for the left eye reflected by the optical path distributing mirror enters the prism, a second surface which reflects the light beam of the optical path for the left eye within the prism, and a third surface through which the light beam of the optical path for the left eye exits from the prism.
At least the second surface of the ocular prism for the right eye, which is a reflecting surface, and the second surface of the ocular prism for the left eye, which is a reflecting surface, have a rotationally asymmetric curved surface configuration that corrects decentration aberrations.
Another image display apparatus according to the present invention has an image display device for displaying an image to be observed by an observer, an optical path distributing prism for distributing the image to an optical path for a right eye and an optical path for a left eye, an ocular prism for the right eye that is placed on the right-hand side of the optical path distributing prism, and an ocular prism for the left eye that is placed on the left-hand side of the optical path distributing prism.
The optical path distributing prism has at least a first surface placed to face the image display device so that a display light beam emanating from the image display device enters the prism through the first surface, a second-first surface which reflects the optical path for the right eye entering through the first surface, a second-second surface which reflects the optical path for the left eye entering through the first surface, a third-first surface through which the light beam of the optical path for the right eye exits from the prism, and a third-second surface through which the light beam of the optical path for the left eye exits from the prism.
To form a relay image for the right eye from the image displayed by the image display device in the optical path for the right eye and to form a relay image for the left eye from the image displayed by the image display device in the optical path for the left eye, the optical path distributing prism is arranged so that at least the second-first surface and the second-second surface have a curved surface configuration that gives a power to the light beam, and the second-first surface and the second-second surface have the same surface configuration.
The ocular prism for the right eye has a first surface through which the light beam of the optical path for the right eye exiting from the third-first surface of the optical path distributing prism enters the prism, a second surface which reflects the light beam of the optical path for the right eye within the prism, and a third surface through which the light beam of the optical path for the right eye exits from the prism.
The ocular prism for the left eye has a first surface through which the light beam of the optical path for the left eye exiting from the third-second surface of the optical path distributing prism enters the prism, a second surface which reflects the light beam of the optical path for the left eye within the prism, and a third surface through which the light beam of the optical path for the left eye exits from the prism.
At least the second surface of the ocular prism for the right eye, which is a reflecting surface, and the second surface of the ocular prism for the left eye, which is a reflecting surface, have a rotationally asymmetric curved surface configuration that corrects decentration aberrations.
With the above-described arrangement, the present invention can provide an image display apparatus, e.g. a head-mounted image display apparatus, in which an image from a single image display device is led to two eyes without using a half-mirror, thereby allowing observation of a bright image, and the correction of various aberrations is facilitated by placing an optical path distributing mirror or an optical path distributing prism at the middle between the two eyes. Further, it is possible to obtain an illuminating arrangement which is the most suitable for observation of a single panel with two eyes, and which can be used in the above-described arrangement without the need to switch the display image for the left and right.
Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.
The invention accordingly comprises the features of construction, combinations of elements, and arrangement of parts which will be exemplified in the construction hereinafter set forth, and the scope of the invention will be indicated in the claims.